// SPDX-License-Identifier: GPL-3.0-or-later
// Copyright (c) 2025 XujueKing <leadbrand@me.com>

// SuperVM 2.0 - Ring Signature Implementation
// 架构师: KING XU (CHINA)
// Phase 2.2.1: Ring Signatures (Week 9-12)
//
// 实现 MLSAG (Multilayered Linkable Spontaneous Anonymous Group) 环签名
// 或 CLSAG (Concise Linkable Spontaneous Anonymous Group) 环签名

use crate::privacy::types::*;
use anyhow::Result;

/// Ring Signature Signer
/// 用于生成环签名
pub struct RingSigner {
    // TODO: Phase 2.2.1 - 添加密钥管理
}

impl RingSigner {
    /// 创建新的签名器
    pub fn new() -> Self {
        todo!("Phase 2.2.1: Implement ring signer")
    }
    
    /// 生成环签名
    /// 
    /// # 参数
    /// - `message`: 要签名的消息
    /// - `secret_key`: 签名者的私钥
    /// - `public_key`: 签名者的公钥
    /// - `ring`: 环成员公钥列表 (包含签名者)
    /// - `secret_index`: 签名者在环中的索引
    /// 
    /// # 返回
    /// 环签名和 Key Image
    pub fn sign(
        &self,
        _message: &[u8],
        _secret_key: &SecretKey,
        _public_key: &PublicKey,
        _ring: &[PublicKey],
        _secret_index: usize,
    ) -> Result<RingSignature> {
        todo!("Phase 2.2.1: Implement MLSAG/CLSAG signing")
    }
}

/// Ring Signature Verifier
/// 用于验证环签名
pub struct RingVerifier {
    // TODO: Phase 2.2.1 - 添加验证逻辑
}

impl RingVerifier {
    /// 创建新的验证器
    pub fn new() -> Self {
        todo!("Phase 2.2.1: Implement ring verifier")
    }
    
    /// 验证环签名
    /// 
    /// # 参数
    /// - `message`: 原始消息
    /// - `signature`: 环签名
    /// 
    /// # 返回
    /// 验证是否通过
    pub fn verify(&self, _message: &[u8], _signature: &RingSignature) -> Result<bool> {
        todo!("Phase 2.2.1: Implement MLSAG/CLSAG verification")
    }
    
    /// 检查 Key Image 是否已使用 (防止双花)
    pub fn is_key_image_spent(&self, _key_image: &KeyImage) -> bool {
        todo!("Phase 2.2.1: Implement key image tracking")
    }
}

/// 随机选择环成员 (诱饵)
/// 
/// # 参数
/// - `real_index`: 真实输出的索引
/// - `ring_size`: 环大小
/// - `total_outputs`: 可选择的总输出数
/// 
/// # 返回
/// 环成员索引列表
pub fn select_ring_members(
    _real_index: usize,
    _ring_size: usize,
    _total_outputs: usize,
) -> Result<Vec<usize>> {
    todo!("Phase 2.2.1: Implement ring member selection")
}

#[cfg(test)]
mod tests {
    use super::*;
    
    #[test]
    #[should_panic(expected = "not yet implemented")]
    fn test_ring_signer_placeholder() {
        let _signer = RingSigner::new();
    }
    
    #[test]
    #[should_panic(expected = "not yet implemented")]
    fn test_ring_verifier_placeholder() {
        let _verifier = RingVerifier::new();
    }
}
